Antidepressants target transporter proteins in the human brain that regulate the levels of neurotransmitters such as serotonin and dopamine. The drugs block the transporters from removing neurotransmitters from nerve-cell synapses, thus having a psychoactive effect. But because these human proteins have been difficult to crystallize, information about the exact way they bind to the drugs has been limited.

New findings reported on Oct. 13 suggest that four types of antidepressants bind with transporter proteins in . . .